1. Field of the Invention
This invention relates to an LED lamp that needs a means for radiating heat to be generated in operation.
2. Description of the Related Art
For example, automobiles are equipped with various lamps such as head lamp, tail lamp, winker lamp and stop lamp. These lamps use a lamp of several watts to tens of watts according to use, and an electric light bulb (hereinafter referred to as bulb) is conventionally used for them. The conventional various lamps are attached in a socket to facilitate the attaching and releasing, and its light section where the lamp is attached has a reflector to converge light in a desired direction.
“Since automobile bulbs are changeable parts, they have a structure to be fitted to a socket. Further, in order to shorten the time required in an attaching step of manufacturing, they are not screw type but insert type. For example, a bulb base section has a convex insert portion to a socket and two electrodes are disposed along both sides of the insert portion. The socket attached to the reflector is provided with built-in contact electrodes to contact the electrodes and a bulb support opening to which the insert portion is fitted. Thus, the attaching or releasing of the bulb can be performed simply by inserting or pulling (see for example, Japanese patent application laid-open No.2001-110210, pages 2–3 and FIG. 2).”
“Some vehicles use an LED stop lamp that has a plurality of red LED lamps with high output, instead of a light bulb. The LED lamp has small and lightweight light emitting elements and, therefore, the socket is unnecessary and a transparent red front panel is further unnecessary. Thus, the entire lamp can be minimized and simplified in structure. Also, it has a long lifetime. Accordingly, it is an optimum lamp for automobiles.”
In recent years, a blue LED with high output is developed other than conventional red LED. Also, a white LED is developed based on the blue LED and some applications thereof begin instead of the conventional bulb. The white LED has a lower power consumption and longer lifetime than bulb. If the price lowers in the future, the white LED will be rapidly popularized.
Commercially available lighting apparatuses (flashlight, key holder etc.) using LED are generally structured such that LED leads are directly soldered to pattern or terminal of printed circuit board and therefore its LED lamp cannot be changed. Furthermore, the soldering is difficult to incorporate in the manufacturing line of automobile lamp and the manufacturing process is complicated thereby. So, it is desired that the LED lamp has such a structure that can be inserted to socket without soldering, like bulb. If so, the LED lamp can be handled as change parts, like bulb.
However, the conventional LED lamp of high output type (high brightness type) with consumption power of several watts to ten or more watts generates substantial amount of heat due to increased current. Especially in tail lamp and winker lamp of automobile, the LED, socket and its peripherals may be overheated because such a lamp is subject to radiation of external light and is frequently placed in a space with bad ventilation and, as a result, heat cannot be sufficiently radiated. Therefore, the temperature of light emitting element will rise and the brightness will lower.